Screw-nut device



Jan. 5, 1965 J. E. MARTENS 3,164,029 SCREW-NUT DEVICE Filed March 7,1961 JACK E. MARTENS Bid i ATTORNEY INVENTOR. Fing. 4

United States Patent O 3,164,629 SCREW-NUT DEWCE Jack E. Martens, Gary,Ind., assigner to The Anderson Company, a corporation of Indiana FiledMar. 7, 1961, Ser. No. dt

7 Claims. (Cl. 74--424.S)

This invention relates to motion-transmitting mechanisms and moreparticularly to motion-transmitting mechanisms of the type including ascrew and an antifriction nut cooperable therewith.

An Object of the invention is to provide an improved motion-transmittingmechanism of the nut-and-screw type.

Another object of the invention is to provide a screwnut type ofmotion-transmitting mechanism which is easily operable under load butwhich will retain an adjusted position under load despite shock andvibration.

Another object of this invention is to provide a screwnut mechanismwherein the nut is provided with a limited frictional force to restrainits free rotation on the screw.

Still another object of this invention is to provide a screw-nut whereinthe roller is braked to restrain uncontrolled free rotation of the nutrelative to the screw.

A further object of the invention is to provide an improved screw-nutoperated telescoping leg assembly particularly adaptable to hospitalbeds.

Other objects and advantages of the invention will become apparent afterthe description hereinafter set forth is considered in conjunction withthe drawing annexed hereto.

FIGURE 1 is an elevational view partially in section of the improvedteiescoping leg assembly of my invention;

FIGURE 2 is an enlarged elevational view of my improvedmotion-transmitting mechanism, partially in section and with the ends ofthe screw brolten away;

FIGUREI 3 is an end View of the device of FlGURE 2;

FIGURE 4 is an elevational view of the carrier or cage portion of themotion-transmitting mechanism; and

FIGURE 5 is a view of the carrier, taken along section line S-S ofFIGURE 4.

FIGURE 1 shows a portion of an outer tubular mem- -ber or leg 1dtelescopingly and adjustably mounted on a tubular inner base member orleg 12. A support member 14- is provided at its sides with a pluralityof apertures for threadedly receiving mounting studs, such as studs 1Sand 16, extending through apertures in leg 10. An Unthreaded reduceddiameter end portion 19 of a helically threaded screw 2t? extendscentrally through support member 14 for rotation therethrough.

A flanged collar 21 is mounted on reduced diameter end portion 19 formounting a thrust bearing 22 adjacent the support member 14.

A bevel gear 2d is secured to end portion 19 on the opposite `side ofsupport member 14 by means of a pin 25. As will be understood by thoseskilled in 'the art, the bevel gears 24 in each of four legs of ahospital Ibed are driven by a system of shafts and bevel gears (notshown) operable by a single crank handle.

A nut member 26, preferably made of steel, is suitably lixed to theinner base leg 12 from above and below by inturned detents 27 so as tobe secured against relative movement axially thereof. The nut member 26cooperates with a plurality of rollers 28 retained in a carrier or ICCcage member 29 surrounding screw 20. The rollers 28 also cooperate witha member 54, to be hereinafter described.

The cage member 29 may be stamped from a flat sheet and rolled into atubular shape, and annular bands 30 and 31 may be staked thereto toretain Lthe shape. The cage member may be embossed as at 33, 34, 35a and351) to provide additional strength, and windows 38, 39 and 4t) may beprovided therein to receive rollers 2S.

Each of the ends of cage member 29 is formed to provide a pair ofaxially extending shoulders, one shoulder of each pair being visible, asindicated at 41 and 42, and a second pair (not visible) positioneddegrees from the one pair and facing in the same peripheral direction.These pairs of shoulders are respectively engageable with a pair of stoppins 44 and 45 (FIGURE 1) extending through screwV Ztl and projectingfrom opposite sides thereof. v Each roller 28 is formed with fourradially enlarged bearing surfaces 47, 48, 49 and Sil for rollinglyengaging the threads of screw 2l). The bearing surfaces 47 and 48 aremaintained in engagement with screw 2d by a raceway 52 formed on theinner periphery of nut member 26. The raceway 52 is substantiallyJ-shaped to radially engage bearing surface 47 and to conform to thelower half of bearing surface 43 for supporting and resisting axialloading.

The bearing surfaces i9 and 5l? are maintained in engagement with screwZtl by a raceway 56 on the inside of member 54. The raceway 56 iscylindrically straight, except in the central portion thereof where itprotrudes radially inwardly between bearing surfaces 49 and 50 asindicated by numeral S1. The nut members 26 and 54 are urged apart by anannular leaf spring Sti spaced therebetween. The member 54 may be madeof a nonmetallic material, nylon having been found very satisfactory. Aspointed out above, the nut member 26 is staked or otherwise xed to innerbase leg 12, and the load on `screw Ztl is transferred to nut member 26by bearing surfaces 48 of rollers 28.

It can be seen that rotation of screw 20 through bevel gear 24 willproduce relative axial movement of nut 25 which in turn will carry innerbase leg 12 linearly extensively with respect to outer leg 1d. Legs 1dand 12 are positioned for relative axial movement but are restrainedagainst relative rdtary movement. A restraining means to preventrelative rotation of the legs is not shown in FIGURE 1; however, thiscan be accomplished by the particular shape of the legs 1@ and 12 or bya cooperating klinear slot or indentation, or by nonrotatably mountingeach ofthe legs to portions of the bed or other elements to be adjusted.

Nut member 26 is normally designed to carry an axial load in onedirection, as can ybe clearly seen in FGURE 2. Annular member 54 beingconstantly urged axially from nut Z6 by spring 58 acts against the sideof bearing surfaces Sil whereby rollers 28 are somewhat restrained orretarded against tree rotation; and bearing 48 is maintained in axialcontact with raceway 52.

Member 54 does not carry any substantial load, but serves as a retardingmember. Thus, while the antifn'ction characteristics imparted by rollers23 permits operation under load, the member 54 helps maintain anadjusted position of the nut 26 and screw Ztl despite shock andvibration. It is apparent that a 4momentary axial jar on the nut-screwmechanism will not readily permit bearing surface 48 of roller 23 tobecome unseated from raceway 52 to permit the roller to move or rollunrestrained or involuntarily along the helical threads of screwmemdescribed.

l claim:

l. A motion-transmitting mechanism comprising in combination: rst andsecond members adapted for relatively linear movement and respectivelyattachable to members to be relatively moved, one of the members iixedlycarrying a nut and the other member rotatably carrying a screw memberoperatively received Within the nut member, said nut member including ahousing having an annular raceway and a portion of reduced diameter todefine axial abutment means, elongate rotatable bearing elementsinterposed between the threads of the screw member and the raceway andadapted to engage the axial abutment means thereby establishing drivingcontact between the screw Land nut whereby rotation of the screw movesthe nut axially ftherealong, and means rotatable with respect to saidnut and urged axially with respect thereto for applying rictional dragto the rotatable elements thereby impeding involuntary rotation.

2. A motion-transmitting mechanism comprising in combination: iirst andsecond members adapted for relatively linear movement and respectivelyattachable to members to be relatively moved, one of [the members xedlycarrying a nut and the other member rotatably carrying a screw memberoperatively received within the nut member, said nut member including ahousing having an annular rac'eway and a portion of reduced diameter todefine axial abutment means, rotatable bearing elements interposedbetween the threads of the screw member arid the raceway and adapted toengage the raceway and axial abutment means `thereby establishingdriving contact between the screw and nut whereby rotation of the screwmoves the nut axially therealong for relative linear movement of iirstand second members, means to space the rotatable elements peripherallyof the threaded member, and additional means rotatable with respect tosaid nut and surrounding the spacing means and urged axially infriotional contact with the rotatable bearing elements to thereby impedetheir voluntary rotation.

3. A motion-transmitting mechanism comprising in combination: iirst andsecond members adapted ror rel tively linear ymovement and respectivelyattachable to members to lbe relatively moved, one of the members xedlycarrying a nut and the other member rotatably carrying a screw memberoperatively received within the nut member and adapted to be rotated,said nut member including a housing having an annular raceway and aportion of reduced diameter to define axial abutment means, rotatablebearing elements interposed between the threads of the screw member andthe raceway and adapted to engage the raceway and axial abutment meansthereby establishing driving contact between the screw and nut wherebyrotation of the screw moves the nut axially therealong and said firstand second member linearly with respect to each other, means spacing therotatable bearing elements peripherallyV of the threaded member, annularmeans surrounding the bearing elements in Contact therewith androtatable with respect to said nut, and resilient CIL d means interposedbetween the nut member and annular means for establishing a frictionaldrag on the rotatable bearing elements with which it is in contact.

4. A motion-transmitting mechanism comprising in combination: first adsecond members adapted for relatively linear movement and respectivelyattacbable to members to be relatively moved, one of the members xedlycarrying a nut and the other member rotatably' carrying a screw memberoperatively received within the nut member, said nut member including ahousing having an annular raceway and a portion of reduced diameter ttodenne axial abutment means, elongate rotatable elements havingspaced-apart radially enlarged bearing surfaces interposed between thethreads of the screw member and the raceway and adapted to engage theaxial abutment means thereby establishing driving Contact between thescrew and nut whereby rotation of the screw moves the nut axiallytherealong, cage means spacing the rotatable bearing elementsperipherally of the threaded member, and means spaced axially from thenut member and rotatable with respect thereto and resilienly urged intofrictional contact with the rotatable elements thereby impeding theirinvoluntary rotation.

5. A motion-transmitting mechanism comprising in combination: rst andsecond members adapted for relatively linear movcmcnt and respectivelyattachable to members to be relatively moved, one of the members ixedlycarrying a nut and :the other member rotatably carrying a screw memberoperatively received within the nut member, said nut member including ahousing having an annular raceway and a portion of reduced diameter todenne axial abutment means, elongate rotatable elements havingspaced-apart radially enlarged bearing surfaces internosed between thethreads of the screw member and the raceway and adapted to engage theaxial abutment means thereby establishing driving contact between thescrew and nut whereby rotation of the screw moves lthe nut axiallytberealong, cage means spacing the rotatable bearing elementsperipherally of the threaded member, annular means spaced axially fromthe nut member adjacent an additional radially enlarged bearing surfaceand including resilient means urging the brake means into frictionalcontact with said additional radially enlarged bearing surface to impedetheir rotation, said annular means being rotatable with respect to saidnut in response to a force ,to overcome said resilient means.

6. A motion-transmitting mechanism comprising in combination: first andsecond members adapted for relatively linear movement and respectivelyattachable to members to be relatively moved, one of the members lixedlycarrying a nut and fthe other member rotatably carrying a screw memberoperatively received within the nut member, said nut mem-ber including ahousing having an annular raceway and a portion of reduced diameter todefine axial abutment means, elongate rotatable elements havingspaced-apart radially enlarged bearing surfaces interposed between thethreads of the screw member and the raceway and adapted to engage theaxial abutment means thereby establishing driving contact between thescrew and nut whereby rotation of the screw moves the nut axiallytherealong, cage means spacing the rotatable bearing elementsperipherally of the threaded member, and `annular means spaced axiallyfrom the nut member and rotatably mounted with respect thereto, saidannular means including resilient means adjacent the nut member urgingsaid Iannular means into axial frictional Contact with ythe radiallyenlarged bearing suraces to impede rotation of another of said rotatableelements.

7. A motion-transmitting mechanism comprising in combination: rst andsecond members adapted for relatively linear movement and respectivelyattacbable to members to be relatively moved, one of the members xedlycarrying a nut and the other member rotatably carrying a screw memberoperatively' received within the nut member, said nut member including ahousing having an annular raeeway and a particn of reduced diameter todene axial abutment means, elongate rotatable elements havingspaced-apart radially enlarged bearing surfaces interposed between thethreads of the screw member and the raceway and adapted to engage theaxial abutment means thereby establishing driving Contact between thescrew and nut whereby rotation of the screw moves the nut axiallytherealong, and means rotatably mounted with respect to the nut memberand adapted to be urged into axial contact with another radiallyenlarged bearing surface of said elongate rotatable elements to therebyestablish frictional drag thereon to impede involuntary rotation of thenut member with respect to the screw member.

References Cited in the le of this patent UNITED STATES PATENTS2,623,403 Terdina Dec. 30, 1952 2,757,548 Smith et al. Oct. 7, 19542,842,978 Orner July 15, 1958 2,919,596 Kuehl Jan. 5, 1960 2,966,071Wise Dec. 27, 1960 2,979,965 Diebold Apr. 18, 1961 3,014,380 MartensDec. 26, 1961 OTHER REFERENCES Publication: Ball Bearing Screw andSpline Operation; Saginaw Steering Gear Divsion-General Motors Corp.,Saginaw, Michigan; September 6-16, 1960, page 16. (Copy in Div. 12.)

UNlTED STATES PATENT OFFICE CERTiFiCArE oF ConRECTloN' Patent No A3,164,029 January '5 l965 Jack E. Martens l l lt is herab-5r certified'thaterror appears in the above numb-ered patg ent requiring correction andthat the said Letters Patent should read as corrected below.

Column 3, line 55, Jfor "voluntary" read involuntary-q column 4, line 67Jfor "the radially enlarged bearing surfaces read another of saidradially enlarged bearing surzEaCres line 68, for "rotation of anotherof said rotatable elements" read rotation of the rotatable elementsSigned and sealed this 24th day of August 1965.

(SEAL) A nest:

ERNEST W. SWIDER EDWARD J BRENNER, Attesting Officer Commissioner ofPatents

1. A MOTION-TRANSMITTING MECHANISM COMPRISING IN COMBINATION: FIRST ANDSECOND MEMBERS, ADAPTED FOR RELATIVELY LINEAR MOVEMENT AND RESPECTIVELYATTACHABLE TO MEMBERS TO BE RELATIVELY MOVED, ONE OF THE MEMBERS FIXEDLYCARRYING A NUT AND THE OTHER MEMBER ROTATABLY CARRYING A SCREW MEMBEROPERATIVELY RECEIVED WITHIN THE NUT MEMBER, SAID NUT MEMBER INCLUDING AHOUSING HAVING AN ANNULAR RACEWAY AND A PORTION OF REDUCED DIAMETER TODEFINE AXIAL ABUTMENT MEANS, ELONGATE ROTATABLY BEARING ELEMENTSINTERPOSED BETWEEN THE THREADS OF THE SCREW MEMBER AND THE RACEWAY ANDADAPTED TO ENGAGE THE AXIAL ABUTMENT MEANS THEREBY ESTABLISHING DRIVINGCONTACT BETWEEN THE SCREW AND NUT WHEREBY ROTATION OF THE SCREW MOVESTHE NUT AXIALLY THEREALONG, AND MEANS ROTATABLE WITH RESPECT TO SAID NUTAND URGED AXIALLY WITH RESPECT THERETO FOR APPLYING FRICTIONAL DRAG TOTHE ROTATABLE ELEMENTS THEREBY IMPEDING INVOLUNTARY ROTATION.